1. Field of the Invention
Aspects of the present invention relate to a transient voltage suppressor and its manufacturing method.
2. Description of the Related Art
Referring to FIG. 1, a circuit view for the operating principle of a general transient voltage suppressor is illustrated. As illustrated in FIG. 1, the general transient voltage suppressor (TVS) (e.g., a varistor, a thyristor, or a diode (rectifier/Zener)) is connected in parallel between a power supply VG and a load RLOAD, and one side of the transient voltage suppressor TVS is connected to a ground (GND).
With this configuration, when an over-voltage exceeding a voltage required by the load RLOAD is input, a transient voltage derived current (ITV) flows toward the ground GND through the transient voltage suppressor TVS and only a low voltage that is clamped and stabilized is applied to the load RLOAD, thereby safely protecting the load RLOAD from the transient voltage.
The transient voltage suppressor TVS is affected by capacitance and electrostatic discharge (ESD). In order to increase an ESD characteristic of the transient voltage suppressor TVS, which is generally comprised of a single element, it is necessary to increase an area of the transient voltage suppressor TVS. However, when the area of the transient voltage suppressor TVS is increased, a contact area of a substrate and a doping region may be increased and a capacitance value may be increased accordingly. The increase in the capacitance value of the transient voltage suppressor TVS may severely distort signals, making it difficult to adopt the transient voltage suppressor TVS to a high-frequency circuit. In addition, since a breakdown voltage of the transient voltage suppressor TVS is considerably affected by a concentration difference between the substrate and the doping region, affecting the overall current flowing throughout the transient voltage suppressor TVS. Accordingly, internal resistance of the transient voltage suppressor TVS may be increased, thereby reducing an electrostatic withstand voltage.